Semiconductor-based selective emitter with a sharp cutoff for thermophotovoltaic energy conversion

Abstract

A semiconductor emitter can possibly achieve a sharp cutoff wavelength due to its intrinsic bandgap absorption and almost zero sub-bandgap emission without doping. A germanium-wafer-based selective emitter with front-side antireflection and backside metal coating is studied here for thermophotovoltaic (TPV) energy conversion. Optical simulation predicts the spectral emittance above 0.9 in the wavelengths from 1 to 1.85 µm and below 0.2 in the sub-bandgap range with a sharp cutoff around the bandgap, indicating superior spectral selectivity behavior. This is confirmed by excellent agreement with indirectly measured spectral emittance of the fabricated Ge-based selective emitter sample. Furthermore, the TPV efficiency by pairing the Ge-based selective emitter with a GaSb cell is theoretically analyzed at different temperatures. This Letter facilitates the development of the semiconductor-based selective emitters for enhancing TPV performance.

High-Selectivity Planar Thermal Emitter with a Stable Temperature over 1400 K for a Thermophotovoltaic System

“…However, the complex geometry and the complicated fabrication process give rise to high manufacturing costs of the emitters, and it is difficult to guarantee their thermal stability in long-term high-temperature service. Spectrally selective thermal emitters with multilayer structures based on transition metal oxides, , refractory metals, , heavily doped semiconductors, and metal/dielectric coatings, , etc., can enable large-area fabrication. However, these emitters suffer from inferior spectral selectivity and relatively low stable temperature (<1273 K), unsuitable for practical TPV systems.…”

Spectrum‐Selective High‐Temperature Tolerant Thermal Emitter by Dual‐Coherence Enhanced Absorption for Solar Thermophotovoltaics

“…[7,11] Basically, a well-designed STPV system should contain an absorberemitter component to realize ideal step functionalized absorption-emission spectra and to raise the operating temperature, [12] an efficient energy conversion process with photovoltaics (PV) cell, [13,14] and an effective regulation for thermal insulation. [12] According to Kirchhoff's law, absorption spectra instead of emission spectra are calculated in design to realize the perfect absorption through semiconductors, [15] nanoparticles, [16] and refractory metallic structures. [17][18][19] As one of the approaches, coherent perfect absorption (CPA) can be applied to reshape the spectra and control the heat transfer, [20,21] even in the waveguide, [22] random system, [23] etc.…”

Design and Spectral Performance of HfO2-Based Multilayer Spectrally Selective Emitters Embedded with VO2 Nanoparticles

“…Thermophotovoltaic (TPV) systems convert directly thermal energy into electricity, having a high theoretical conversion efficiency that can exceed the Shockley–Queisser limit. − Emitters are significant components in TPV systems, playing an important role in emitting thermal energy to PV cells. , Because only the radiation energy above the bandgap of the PV cell can be converted, , spectrally selective emitters are required for the development of TPV systems.…”

“…1−4 Emitters are significant components in TPV systems, playing an important role in emitting thermal energy to PV cells. 5,6 Because only the radiation energy above the bandgap of the PV cell can be converted, 7,8 spectrally selective emitters are required for the development of TPV systems.…”